1. Field of the Invention
This invention generally relates to mechanisms and methods for feeding pins. More particularly, this invention relates to methods and mechanisms for feeding and holding pins for use with electrical circuit board assemblies. The subject matter of the present invention finds application in production assembly lines where a large number of pins are to be assembled to electrical circuit boards using automatic or semi-automatic production machinery and assembly techniques. Prior to this invention, several methods of holding pins prior to insertion in a circuit board were known. One of these methods involves the use of a hand-operated press for staking pins into a circuit board. A lower die containing a bore is utilized to hold a manually inserted pin in position while a circuit board containing a hole is placed over the pin and the pin is staked in position using a punch connected to a manually or pneumatically operated ram. Manual insertion of the pins into the die is a time consuming, inefficient operation. In many cases such a manually operated and loaded system must be used for repair work because semiautomatically loading machines do not allow rework on a circuit board because other pins already inserted into the circuit board interfere with the feed mechanisms of such machines.
Another type of prior art pin holder contains a feed mechanism located in the same plane as the apparatus for holding the pin in position. Such feed mechanisms include a housing containing a slot for guiding a pin from a remote feed point to the final holding point. A push rod pushes the pin from the feed point through the slot to the final holding position where a pair of jaws holds the pin in position. The feed rod is required to push the pin through the slot a considerable distance, causing a skilled operator to wait while a pin is pushed into position. Another disadvantage of this system is that the feed mechanism lies in the same plane as the holding jaws so that a predetermined sequence of pin insertions must be followed in order that pins already inserted in a circuit board do not interfer with the guide slot housing. Reworking circuit boards with components already inserted causes the already inserted components to interfere with the guide slot housing, requiring an insertion of reworked terminals on a manually operated press as mentioned previously.
Consequently, the holding of pins in holes and circuit boards has presented problems which are expensive and time consuming in a automatic or semi-automatic production assembly environment.
2. SUMMARY OF THE INVENTION
Accordingly, an object of this invention is to provide an improved apparatus and method for feeding and holding pins for insertion in electrical circuit boards.
Another object of this invention is to provide a mechanism by which pins may be inserted in a circuit board in a variety of locations.
Another object of this invention is to provide a semiautomatic, sequential feed mechanism having a low duty cycle for high production rates.
Another object of this invention is to provide a feed mechanism for pins which includes an integral clamping structure to hold said pins.
Another object of this invention is to provide a method for sequentially feeding and holding pins for high-speed semi-automatic production assembly.
Another object of this invention is to provide a method for holding a pin while a work piece is positioned over said pin and for holding said pin while a portion of said pin is being deformed with a punch to lock said pin in place.
Briefly, the invention consists of a sequential magazine feed and holding apparatus for pins to be inserted in a work piece, such as an electrical circuit board. A collet means is provided having a longitudinal bore extending therethrough from a feed end to a holding end for receiving, transporting, and holding a pin. A feed means for sequentially feeding a pin into the feed end of said collet bore and a transport means for transporting the pin from the feed end to the holding end of said collet are provided along with a holding means for predeterminedly holding the pin in the holding end of said collet. The holding end of the collet has at least one longitudinal slot to permit variations in the bore cross sectional area. A push rod pushes the pin into position through the bore of the collet. The pin is clamped into position in the collet by means of a sleeve around said collet, said sleeve and said collet having portions which cooperate to clamp said pin when said collet and said sleeve are moved longitudinally with respect to each other. The magazine feed means includes an indexable disc having peripheral cutouts for receiving and containing the pins urged therein. Said disc is indexed to sequentially bring said disc cutouts into alignment with the feed end of the collet bore. The disc may be indexed, for example by a pawl and ratchet arrangement. A pin may be attached to a work piece, such as a circuit board, by holding the pin within the holding end of the collet as described and having a punch coaxial with said collet bore to deform a deformable portion of said pins thereby locking said pin in the work piece.
A method for sequentially feeding and holding pins is disclosed comprising the steps of sequentially feeding a pin into position near a feed end of a collet means having a bore extending therethrough from the feed end to a holding end and transporting a pin from the feed end to the holding end. The pin is held in the holding end of said collet means bore and a further step of deforming said pin to attach said pin to a work piece may be performed with a punch means coaxial with said collet bore.